1. Field of the Invention
The invention relates generally to brake systems for wheeled vehicles. More particularly, the invention is directed to the brake component mounting brackets that are connected to the axle of the vehicle. More specifically, the invention is directed to a heavy-duty vehicle brake system component axle mount for trucks and tractor-trailers, in which the mounting brackets for the brake system components are securely and efficiently connected to the axle by a peened connection. The peened connection imparts desirable compressive stresses to critical high stress areas of the mounting bracket-to-axle connection, thereby increasing durability of the bracket-to-axle connection as well as durability of the axle. The improved durability of the bracket-to-axle connection and improved durability of the axle provides the opportunity, if desired, to use a thinner, and therefore lighter, axle, which in turn can potentially provide cost and weight savings to the axle/suspension system.
2. Background Art
The use of air-ride trailing and leading arm rigid beam-type axle/suspension systems has been very popular in the heavy-duty truck and tractor-trailer industry for many years. Air-ride trailing and leading arm spring beam-type axle/suspension systems also are often used in the industry. For the purpose of convenience and clarity, reference herein will be made to beams, with the understanding that such reference is by way of example, and that the present invention applies to heavy-duty vehicle air-ride axle/suspension systems that utilize rigid-type beams or spring-type beams, and also to heavy-duty vehicle mechanical axle/suspension systems, such as non-air-ride leaf spring systems. Although such axle/suspension systems can be found in widely varying structural forms, in general their structure is similar in that each system typically includes a pair of suspension assemblies. In some heavy-duty vehicles, the suspension assemblies are connected directly to the primary frame of the vehicle. In other heavy-duty vehicles, the primary frame of the vehicle supports a subframe, and the suspension assemblies connect directly to the subframe. For those heavy-duty vehicles that support a subframe, the subframe can be non-movable or movable, the latter being commonly referred to as a slider box, slider subframe, slider undercarriage, or secondary slider frame. For the purpose of convenience and clarity, reference herein will be made to main members, with the understanding that such reference is by way of example, and that the present invention applies to heavy-duty vehicle axle/suspension systems suspended from main members of: primary frames, movable subframes and non-movable subframes.
Specifically, each suspension assembly of an axle/suspension system includes a longitudinally extending elongated beam. Each beam typically is located adjacent to and below a respective one of a pair of spaced-apart longitudinally extending main members and one or more cross members which form the frame of the vehicle. More specifically, each beam is pivotally connected at one of its ends to a hanger, which in turn is attached to and depends from a respective one of the main members of the vehicle. The beams of the axle/suspension system can either be an overslung/top-mount configuration or an underslung/bottom-mount configuration. For the purposes of convenience and clarity, hereinafter a beam having an overslung/top-mount configuration will be referred to as an overslung beam with the understanding that such reference is by way of example, and that the present invention applies to both overslung/top-mount configurations and underslung/bottom-mount configurations. An axle extends transversely between and typically is connected by some means to the beams of the pair of suspension assemblies at a selected location from about the mid-point of each beam to the end of the beam opposite from its pivotal connection end. The opposite end of each beam also is connected to a bellows air spring or its equivalent, which in turn is connected to a respective one of the main members. A height control valve is mounted on the frame and is operatively connected to the beam in order to maintain the ride height of the vehicle. The beam may extend rearwardly or frontwardly from the pivotal connection relative to the front of the vehicle, thus defining what are typically referred to as trailing arm or leading arm axle/suspension systems, respectively. However, for purposes of the description contained herein, it is understood that the term “trailing arm” will encompass beams which extend either rearwardly or frontwardly with respect to the front end of the vehicle. One or more shock absorbers and a brake assembly also are mounted on the axle/suspension system.
Conventional heavy-duty vehicle brake systems typically include a brake assembly for each suspension assembly and its associated wheel. The brake assembly components typically include a brake chamber, a piston, a slack adjuster, and an S-cam assembly. The S-cam assembly includes a cam shaft and an S-cam which is utilized to move brake shoes against a brake drum of the vehicle wheel to decelerate the vehicle. The cam shaft typically is supported at each of its ends. More particularly, the outboard end of the cam shaft is supported by a brake spider which in turn is mounted on the axle. The inboard end of the cam shaft is supported by a cam shaft bracket. The brake spider and the cam shaft bracket each support a bearing to enable rotation of the cam shaft during operation of the vehicle. In certain applications the cam shaft bracket is welded directly to the axle, which provides stability to the inboard end of the cam shaft and its bearing, and in turn to the entire brake assembly. The brake chamber is also mounted on the axle via a brake chamber bracket, which also, in certain applications, is welded directly to the axle.
More specifically, the welding of the brake chamber bracket and the cam shaft bracket directly to the axle can potentially create significant stress risers and local mechanical property changes in the axle, as is generally well known in the art. These stress risers and local mechanical property changes in the axle can in turn potentially reduce the durability/life expectancy of the axle and the bracket-to-axle connection. This reduction in durability/life expectancy can be counteracted by providing a thicker walled axle, but this adds both weight and cost to the axle.
The brake system component axle mount of the present invention overcomes the aforementioned potential problems associated with axle/suspension systems that utilize prior art brake chamber brackets and cam shaft brackets, by providing a peened connection between each of the brackets and the axle, which imparts desirable compressive stresses to critical high stress areas of the mounting bracket-to-axle connection, thereby increasing durability of the bracket-to-axle connection as well as durability of the axle. The resulting improved durability of the bracket-to-axle connection and the axle provides the opportunity if desired to use a thinner, and therefore lighter, axle, which in turn can potentially provide cost and weight savings to the axle/suspension system.